Itching is an unpleasant sensation that triggers the urge to scratch. It is a fairly common ailment that usually turns out to be harmless. If the itching affects only one part of the body it is usually caused by a skin disease. Itching all over the body may be caused by systemic disease.

What is pruritus, and what is the mechanism of its formation?

Itching is an unpleasant sensation in the skin that makes you need to scratch or rub. The mechanism of pruritus is multifactorial and complicated. It may have a source both in the nervous system and result from the action of mechanical, chemical, thermal or electrical stimuli on nerve fibers.

Pruritus that lasts 6 weeks or more is defined as chronic.

What are the most common causes of itching?

Itching may affect selected areas of the skin or the entire body. In the case of localized itching, the most common causes are skin diseases, such as: bacterial, viral (herpes), fungal (dandruff, mycosis), parasitic (scabies,lice),atopic dermatitis,urticaria, eczema,psoriasis, excessive dry skin, burns, sun exposure, bites of insects and other animals,food allergies, drug allergies, cosmetics, chemicals, skin disorders cancer .

Whole body itching is a consequence of systemic diseases in about 10–50% of people experiencing it.

Causes of generalized pruritus:

1. allergic skin diseases
2. chronic renal failure
3. diseases of the liver and biliary tract
   • primary cholangitis
   • primary or secondary sclerosing cholangitis
   • extrahepatic cholestasis
   • cholestasis in pregnant women
   • hepatitis
4. diseases of the hematopoietic system
   • polycythemia true
   • Hodgkin’s lymphoma
   • mycosis fungoides
   • other lymphoproliferative and myeloproliferative neoplasms
   • mastocytosis
   • iron deficiency
5. endocrine and metabolic disorders: diseases of the thyroid gland, parathyroid glands, diabetes,carcinoid syndrome,hypercalcemia
6. malignant tumors
7. neuropathies
   • diseases of the central nervous system – brain tumors and abscesses, post-stroke lesions, aneurysms,multiple sclerosis
   • diseases of the nervous system with nerve damage –shingles, diabetes, amyloidosis, drug-induced, in the postoperative scar
   • Nerve pinching or entrapment: notalgia paresthetica, brachial-radial pruritus
8. HIV infection
9. medications (e.g. opioids, anti-EGFR monoclonal antibodies, tyrosine kinase inhibitors), oral contraceptives
10. psychogenic (nervous) itching.

Itching – treatment

Itching is a fairly common condition that usually turns out to be harmless. If symptoms occur, you should consider the possible simple causes of the condition. The itching can usually be controlled at home. The following measures are helpful in relieving itch at home:

• moisturizing the skin with creams, lotions or oils – at least once a day,
• cold compresses,
• lotions with menthol (0.125-2%, most often 1%), phenol (0.125-2%) or camphor (0.1-3%),
• the beneficial effect is also observed after therapeutic baths with oatmeal, baking soda or essential oils.
• in the case of itching associated with macerated skin (skin that has been in high contact with moisture, usually wrinkled and lighter), care is to gently remove moisture by using cold air from a dryer and wet compresses left to dry completely, and to prevent the build-up of discharge
• taking over-the-counter oral antihistamines, such as cetirizine or loratadine,
• applying cool compresses or bandages to particularly irritating places, which, in addition to alleviating itching, protects them from scratching,
• avoiding scratching, which usually only exacerbates symptoms. It can be helpful to cut your nails and wear gloves when you go to sleep to avoid unknowingly scratching overnight.
• using soap free of fragrances and dyes for washing the body, thoroughly rinsing the body after bathing,
• avoiding strong detergents, excluding the use of newly bought powders, softeners or bleaches,
• avoiding substances that may irritate the skin – chemicals for cleaning, perfumed waters and other cosmetics, jewelry that may contain nickel,
• wearing clothes made of delicate materials,
• avoiding stress, which can make itching worse.

Situations where a feeling of itching should prompt you to see a doctor include:

• itching that lasts more than a week, does not respond to home methods of reducing it,
• persistent itching that prevents normal functioning during the day, impairs sleep,
• no apparent cause of itching
• itching with symptoms such as extreme tiredness, weight loss, changes in bowel habits,fever,jaundiceand extensive skin changes.

Itching – examination

The doctor will begin the visit by collecting a thorough history with the patient, which will include questions about:

• onset of symptoms and their duration,
• the nature of the pruritus (location, build-up over time, factors increasing or relieving the pruritus),
• measures taken so far to combat itching with home remedies,
• recent changes in the washing and cleaning agents used, contact with chemicals, animals,
• current diet,
• allergies,
• past and accompanying chronic diseases,
• medications taken, including herbal medicines, over-the-counter medicines, dietary supplements.

Next, an examination will be performed, with particular emphasis on the skin lesions in the area most affected by itching. In order to exclude systemic diseases that may be the cause of the presented symptoms, the doctor may order additional tests, including blood laboratory tests (including blood counts, inflammation markers, thyroid hormone levels), allergicskin tests, taking a sample of lesions on the skin to performing microbiological tests.

Further management depends on the likely cause of the pruritus.